1. Field of the Invention
The present invention relates to an MEMS component, whose micromechanical structure is realized in a layered structure on a substrate, individual components of the micromechanical structure being essentially configured in each case in a mechanical functional layer of this layered structure.
2. Description of the Related Art
An MEMS component of this type is described, for example, in U.S. Pat. No. 6,535,460 B2. Here, the MEMS component includes a micromechanical microphone structure having an acoustically active diaphragm that is configured in a first mechanical functional layer and spans a sound port in the substrate rear side. A fixed counter element is configured in another mechanical functional layer above the diaphragm, spaced apart from the same. The counter element has perforations, making it acoustically transmissive. The signals are acquired capacitively in that the diaphragm functions as a movable electrode and, together with a fixed electrode on the counter element, forms a capacitor system. The layered structure and the microphone structure of the known MEMS microphone component are produced using microsystems technology, semi-conductive, dielectric, metallic and/or plastic-based layered materials being used.
In the case of mechanical functional layers of micromechanical components of this kind, it is mostly a question of layers of semiconductive material and/or of layers of dielectric material that are deposited at very high temperatures ranging from 500° C. to over 1000° C. In this case, only thin-layer materials and processes may be used beforehand in the manufacturing process that withstand the high deposition temperatures. It is important that the temperatures that the component is subject to during the manufacture thereof do not lead to an unintentional change in the properties of the individual layers of the layered structure, such as, for example, to a change in the layer strain or in the layer conductivity caused by a compression of the initially polycrystalline layer material. This can result, namely, in cracks forming in individual layers, for example, and/or in high stress gradients within the layered structure that lead to deformation of the component structure. Plastics can then be used only in the course of the manufacturing process, for example, as a passivation or sacrificial layer, when the subsequent processes are carried out at temperatures significantly below the decomposition temperature of the plastic material.
Metals, such as aluminum, for example, may, in fact, be deposited at lower temperatures. However, they have a tendency to creep already under low mechanical loads, which, in the case of a multiple occurrence, can lead over the long term to irreversible deformations of mechanical functional elements, respectively to a change in the mechanical properties thereof. This then manifests itself as drift of the component signal. Moreover, the originally adjusted mechanical strain condition changes at high temperatures, as occur, for example, during the soldering process or during thermal cycling.